This invention relates to a roll of the type having a hollow outer roll forming the working roll circumference braced against a cross head extending therethrough. The outer roll is braced against the inner roll by means of a pressure medium supplied by a feed line to a chamber formed between the outer roll and cross head by longitudinal and transverse seals. External forces may be applied to the ends of the cross head protruding from the hollow roll.
Rolls of this type in which the bracing of the outer roll against the cross head is by means of a pressure medium in a chamber formed therebetween, with different designs of the longitudinal and transverse end seal needed to seal off the chamber, are known from German Pat. Nos. 11 93 739, 20 25 777 and 27 18 414. There, the transverse end seals are designed as sliding ring seals or sliding strip seals which are connected to the cross head and rest against a radial flange connected to the revolving hollow roll. The pressure of the liquid in the chamber acts against the sliding strips, i.e., they make contact with the radial flange against the sliding surface with a force proportional to this pressure.
Long years of experience have shown that these rolls work satisfactorily as long as the pressure in the chamber is less than about 25 bar. For the use of such rolls in the paper, textile and plastic industry, this pressure is entirely sufficient.
If, however, the pressure in the chamber is increased beyond 25 bar, the friction of the seals at the counter surfaces increases so that appreciable power losses occur and, in addition, rapidly increasing wear is observed. This is of great concern particularly because rolls are basically continuously running elements and replacing a roll means considerable effort and in many cases a shutdown of an entire production line.
If, however, rolls of the type under discussion now are to be used for the processing of metals, higher pressures are required, which also necessitate higher pressures in the chamber.
While it is known in principle from the literature reference "Melliand Textilberichte" 8/53 (1972), pages 935 to 940, to also use so-called floating rolls of this general type in the steel industry, this requires special designs because of the higher pressures.
It is an object of the present invention to design a roll of the type described above, in such a way that no excessive friction losses and no wear occur at the transverse end seals even at higher pressures.